2 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
7 * or rs-channels. It also implements echoing, cooked mode etc.
9 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
11 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
12 * tty_struct and tty_queue structures. Previously there was an array
13 * of 256 tty_struct's which was statically allocated, and the
14 * tty_queue structures were allocated at boot time. Both are now
15 * dynamically allocated only when the tty is open.
17 * Also restructured routines so that there is more of a separation
18 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
19 * the low-level tty routines (serial.c, pty.c, console.c). This
20 * makes for cleaner and more compact code. -TYT, 9/17/92
22 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
23 * which can be dynamically activated and de-activated by the line
24 * discipline handling modules (like SLIP).
26 * NOTE: pay no attention to the line discipline code (yet); its
27 * interface is still subject to change in this version...
30 * Added functionality to the OPOST tty handling. No delays, but all
31 * other bits should be there.
32 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
34 * Rewrote canonical mode and added more termios flags.
35 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
37 * Reorganized FASYNC support so mouse code can share it.
38 * -- ctm@ardi.com, 9Sep95
40 * New TIOCLINUX variants added.
41 * -- mj@k332.feld.cvut.cz, 19-Nov-95
43 * Restrict vt switching via ioctl()
44 * -- grif@cs.ucr.edu, 5-Dec-95
46 * Move console and virtual terminal code to more appropriate files,
47 * implement CONFIG_VT and generalize console device interface.
48 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
50 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
51 * -- Bill Hawes <whawes@star.net>, June 97
53 * Added devfs support.
54 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
56 * Added support for a Unix98-style ptmx device.
57 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
59 * Reduced memory usage for older ARM systems
60 * -- Russell King <rmk@arm.linux.org.uk>
62 * Move do_SAK() into process context. Less stack use in devfs functions.
63 * alloc_tty_struct() always uses kmalloc()
64 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
67 #include <linux/types.h>
68 #include <linux/major.h>
69 #include <linux/errno.h>
70 #include <linux/signal.h>
71 #include <linux/fcntl.h>
72 #include <linux/sched.h>
73 #include <linux/interrupt.h>
74 #include <linux/tty.h>
75 #include <linux/tty_driver.h>
76 #include <linux/tty_flip.h>
77 #include <linux/devpts_fs.h>
78 #include <linux/file.h>
79 #include <linux/fdtable.h>
80 #include <linux/console.h>
81 #include <linux/timer.h>
82 #include <linux/ctype.h>
85 #include <linux/string.h>
86 #include <linux/slab.h>
87 #include <linux/poll.h>
88 #include <linux/proc_fs.h>
89 #include <linux/init.h>
90 #include <linux/module.h>
91 #include <linux/device.h>
92 #include <linux/wait.h>
93 #include <linux/bitops.h>
94 #include <linux/delay.h>
95 #include <linux/seq_file.h>
96 #include <linux/serial.h>
97 #include <linux/ratelimit.h>
99 #include <linux/uaccess.h>
101 #include <linux/kbd_kern.h>
102 #include <linux/vt_kern.h>
103 #include <linux/selection.h>
105 #include <linux/kmod.h>
106 #include <linux/nsproxy.h>
108 #undef TTY_DEBUG_HANGUP
110 #define TTY_PARANOIA_CHECK 1
111 #define CHECK_TTY_COUNT 1
113 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
114 .c_iflag = ICRNL | IXON,
115 .c_oflag = OPOST | ONLCR,
116 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
117 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
118 ECHOCTL | ECHOKE | IEXTEN,
124 EXPORT_SYMBOL(tty_std_termios);
126 /* This list gets poked at by procfs and various bits of boot up code. This
127 could do with some rationalisation such as pulling the tty proc function
130 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
132 /* Mutex to protect creating and releasing a tty. This is shared with
133 vt.c for deeply disgusting hack reasons */
134 DEFINE_MUTEX(tty_mutex);
135 EXPORT_SYMBOL(tty_mutex);
137 /* Spinlock to protect the tty->tty_files list */
138 DEFINE_SPINLOCK(tty_files_lock);
140 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
141 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
142 ssize_t redirected_tty_write(struct file *, const char __user *,
144 static unsigned int tty_poll(struct file *, poll_table *);
145 static int tty_open(struct inode *, struct file *);
146 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
148 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
151 #define tty_compat_ioctl NULL
153 static int __tty_fasync(int fd, struct file *filp, int on);
154 static int tty_fasync(int fd, struct file *filp, int on);
155 static void release_tty(struct tty_struct *tty, int idx);
156 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
157 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
160 * alloc_tty_struct - allocate a tty object
162 * Return a new empty tty structure. The data fields have not
163 * been initialized in any way but has been zeroed
168 struct tty_struct *alloc_tty_struct(void)
170 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
174 * free_tty_struct - free a disused tty
175 * @tty: tty struct to free
177 * Free the write buffers, tty queue and tty memory itself.
179 * Locking: none. Must be called after tty is definitely unused
182 void free_tty_struct(struct tty_struct *tty)
187 put_device(tty->dev);
188 kfree(tty->write_buf);
189 tty_buffer_free_all(tty);
190 tty->magic = 0xDEADDEAD;
194 static inline struct tty_struct *file_tty(struct file *file)
196 return ((struct tty_file_private *)file->private_data)->tty;
199 int tty_alloc_file(struct file *file)
201 struct tty_file_private *priv;
203 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
207 file->private_data = priv;
212 /* Associate a new file with the tty structure */
213 void tty_add_file(struct tty_struct *tty, struct file *file)
215 struct tty_file_private *priv = file->private_data;
220 spin_lock(&tty_files_lock);
221 list_add(&priv->list, &tty->tty_files);
222 spin_unlock(&tty_files_lock);
226 * tty_free_file - free file->private_data
228 * This shall be used only for fail path handling when tty_add_file was not
231 void tty_free_file(struct file *file)
233 struct tty_file_private *priv = file->private_data;
235 file->private_data = NULL;
239 /* Delete file from its tty */
240 void tty_del_file(struct file *file)
242 struct tty_file_private *priv = file->private_data;
244 spin_lock(&tty_files_lock);
245 list_del(&priv->list);
246 spin_unlock(&tty_files_lock);
251 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
254 * tty_name - return tty naming
255 * @tty: tty structure
256 * @buf: buffer for output
258 * Convert a tty structure into a name. The name reflects the kernel
259 * naming policy and if udev is in use may not reflect user space
264 char *tty_name(struct tty_struct *tty, char *buf)
266 if (!tty) /* Hmm. NULL pointer. That's fun. */
267 strcpy(buf, "NULL tty");
269 strcpy(buf, tty->name);
273 EXPORT_SYMBOL(tty_name);
275 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
278 #ifdef TTY_PARANOIA_CHECK
281 "null TTY for (%d:%d) in %s\n",
282 imajor(inode), iminor(inode), routine);
285 if (tty->magic != TTY_MAGIC) {
287 "bad magic number for tty struct (%d:%d) in %s\n",
288 imajor(inode), iminor(inode), routine);
295 static int check_tty_count(struct tty_struct *tty, const char *routine)
297 #ifdef CHECK_TTY_COUNT
301 spin_lock(&tty_files_lock);
302 list_for_each(p, &tty->tty_files) {
305 spin_unlock(&tty_files_lock);
306 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
307 tty->driver->subtype == PTY_TYPE_SLAVE &&
308 tty->link && tty->link->count)
310 if (tty->count != count) {
311 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
312 "!= #fd's(%d) in %s\n",
313 tty->name, tty->count, count, routine);
321 * get_tty_driver - find device of a tty
322 * @dev_t: device identifier
323 * @index: returns the index of the tty
325 * This routine returns a tty driver structure, given a device number
326 * and also passes back the index number.
328 * Locking: caller must hold tty_mutex
331 static struct tty_driver *get_tty_driver(dev_t device, int *index)
333 struct tty_driver *p;
335 list_for_each_entry(p, &tty_drivers, tty_drivers) {
336 dev_t base = MKDEV(p->major, p->minor_start);
337 if (device < base || device >= base + p->num)
339 *index = device - base;
340 return tty_driver_kref_get(p);
345 #ifdef CONFIG_CONSOLE_POLL
348 * tty_find_polling_driver - find device of a polled tty
349 * @name: name string to match
350 * @line: pointer to resulting tty line nr
352 * This routine returns a tty driver structure, given a name
353 * and the condition that the tty driver is capable of polled
356 struct tty_driver *tty_find_polling_driver(char *name, int *line)
358 struct tty_driver *p, *res = NULL;
363 for (str = name; *str; str++)
364 if ((*str >= '0' && *str <= '9') || *str == ',')
370 tty_line = simple_strtoul(str, &str, 10);
372 mutex_lock(&tty_mutex);
373 /* Search through the tty devices to look for a match */
374 list_for_each_entry(p, &tty_drivers, tty_drivers) {
375 if (strncmp(name, p->name, len) != 0)
383 if (tty_line >= 0 && tty_line < p->num && p->ops &&
384 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
385 res = tty_driver_kref_get(p);
390 mutex_unlock(&tty_mutex);
394 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
398 * tty_check_change - check for POSIX terminal changes
401 * If we try to write to, or set the state of, a terminal and we're
402 * not in the foreground, send a SIGTTOU. If the signal is blocked or
403 * ignored, go ahead and perform the operation. (POSIX 7.2)
408 int tty_check_change(struct tty_struct *tty)
413 if (current->signal->tty != tty)
416 spin_lock_irqsave(&tty->ctrl_lock, flags);
419 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
422 if (task_pgrp(current) == tty->pgrp)
424 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
425 if (is_ignored(SIGTTOU))
427 if (is_current_pgrp_orphaned()) {
431 kill_pgrp(task_pgrp(current), SIGTTOU, 1);
432 set_thread_flag(TIF_SIGPENDING);
437 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
441 EXPORT_SYMBOL(tty_check_change);
443 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
444 size_t count, loff_t *ppos)
449 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
450 size_t count, loff_t *ppos)
455 /* No kernel lock held - none needed ;) */
456 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
458 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
461 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
464 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
467 static long hung_up_tty_compat_ioctl(struct file *file,
468 unsigned int cmd, unsigned long arg)
470 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
473 static const struct file_operations tty_fops = {
478 .unlocked_ioctl = tty_ioctl,
479 .compat_ioctl = tty_compat_ioctl,
481 .release = tty_release,
482 .fasync = tty_fasync,
485 static const struct file_operations console_fops = {
488 .write = redirected_tty_write,
490 .unlocked_ioctl = tty_ioctl,
491 .compat_ioctl = tty_compat_ioctl,
493 .release = tty_release,
494 .fasync = tty_fasync,
497 static const struct file_operations hung_up_tty_fops = {
499 .read = hung_up_tty_read,
500 .write = hung_up_tty_write,
501 .poll = hung_up_tty_poll,
502 .unlocked_ioctl = hung_up_tty_ioctl,
503 .compat_ioctl = hung_up_tty_compat_ioctl,
504 .release = tty_release,
507 static DEFINE_SPINLOCK(redirect_lock);
508 static struct file *redirect;
511 * tty_wakeup - request more data
514 * Internal and external helper for wakeups of tty. This function
515 * informs the line discipline if present that the driver is ready
516 * to receive more output data.
519 void tty_wakeup(struct tty_struct *tty)
521 struct tty_ldisc *ld;
523 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
524 ld = tty_ldisc_ref(tty);
526 if (ld->ops->write_wakeup)
527 ld->ops->write_wakeup(tty);
531 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
534 EXPORT_SYMBOL_GPL(tty_wakeup);
537 * __tty_hangup - actual handler for hangup events
540 * This can be called by the "eventd" kernel thread. That is process
541 * synchronous but doesn't hold any locks, so we need to make sure we
542 * have the appropriate locks for what we're doing.
544 * The hangup event clears any pending redirections onto the hung up
545 * device. It ensures future writes will error and it does the needed
546 * line discipline hangup and signal delivery. The tty object itself
551 * redirect lock for undoing redirection
552 * file list lock for manipulating list of ttys
553 * tty_ldisc_lock from called functions
554 * termios_mutex resetting termios data
555 * tasklist_lock to walk task list for hangup event
556 * ->siglock to protect ->signal/->sighand
558 void __tty_hangup(struct tty_struct *tty)
560 struct file *cons_filp = NULL;
561 struct file *filp, *f = NULL;
562 struct task_struct *p;
563 struct tty_file_private *priv;
564 int closecount = 0, n;
572 spin_lock(&redirect_lock);
573 if (redirect && file_tty(redirect) == tty) {
577 spin_unlock(&redirect_lock);
581 /* some functions below drop BTM, so we need this bit */
582 set_bit(TTY_HUPPING, &tty->flags);
584 /* inuse_filps is protected by the single tty lock,
585 this really needs to change if we want to flush the
586 workqueue with the lock held */
587 check_tty_count(tty, "tty_hangup");
589 spin_lock(&tty_files_lock);
590 /* This breaks for file handles being sent over AF_UNIX sockets ? */
591 list_for_each_entry(priv, &tty->tty_files, list) {
593 if (filp->f_op->write == redirected_tty_write)
595 if (filp->f_op->write != tty_write)
598 __tty_fasync(-1, filp, 0); /* can't block */
599 filp->f_op = &hung_up_tty_fops;
601 spin_unlock(&tty_files_lock);
604 * it drops BTM and thus races with reopen
605 * we protect the race by TTY_HUPPING
607 tty_ldisc_hangup(tty);
609 read_lock(&tasklist_lock);
611 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
612 spin_lock_irq(&p->sighand->siglock);
613 if (p->signal->tty == tty) {
614 p->signal->tty = NULL;
615 /* We defer the dereferences outside fo
619 if (!p->signal->leader) {
620 spin_unlock_irq(&p->sighand->siglock);
623 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
624 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
625 put_pid(p->signal->tty_old_pgrp); /* A noop */
626 spin_lock_irqsave(&tty->ctrl_lock, flags);
628 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
629 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
630 spin_unlock_irq(&p->sighand->siglock);
631 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
633 read_unlock(&tasklist_lock);
635 spin_lock_irqsave(&tty->ctrl_lock, flags);
636 clear_bit(TTY_THROTTLED, &tty->flags);
637 clear_bit(TTY_PUSH, &tty->flags);
638 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
639 put_pid(tty->session);
643 tty->ctrl_status = 0;
644 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
646 /* Account for the p->signal references we killed */
651 * If one of the devices matches a console pointer, we
652 * cannot just call hangup() because that will cause
653 * tty->count and state->count to go out of sync.
654 * So we just call close() the right number of times.
658 for (n = 0; n < closecount; n++)
659 tty->ops->close(tty, cons_filp);
660 } else if (tty->ops->hangup)
661 (tty->ops->hangup)(tty);
663 * We don't want to have driver/ldisc interactions beyond
664 * the ones we did here. The driver layer expects no
665 * calls after ->hangup() from the ldisc side. However we
666 * can't yet guarantee all that.
668 set_bit(TTY_HUPPED, &tty->flags);
669 clear_bit(TTY_HUPPING, &tty->flags);
670 tty_ldisc_enable(tty);
678 static void do_tty_hangup(struct work_struct *work)
680 struct tty_struct *tty =
681 container_of(work, struct tty_struct, hangup_work);
687 * tty_hangup - trigger a hangup event
688 * @tty: tty to hangup
690 * A carrier loss (virtual or otherwise) has occurred on this like
691 * schedule a hangup sequence to run after this event.
694 void tty_hangup(struct tty_struct *tty)
696 #ifdef TTY_DEBUG_HANGUP
698 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
700 schedule_work(&tty->hangup_work);
703 EXPORT_SYMBOL(tty_hangup);
706 * tty_vhangup - process vhangup
707 * @tty: tty to hangup
709 * The user has asked via system call for the terminal to be hung up.
710 * We do this synchronously so that when the syscall returns the process
711 * is complete. That guarantee is necessary for security reasons.
714 void tty_vhangup(struct tty_struct *tty)
716 #ifdef TTY_DEBUG_HANGUP
719 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
724 EXPORT_SYMBOL(tty_vhangup);
728 * tty_vhangup_self - process vhangup for own ctty
730 * Perform a vhangup on the current controlling tty
733 void tty_vhangup_self(void)
735 struct tty_struct *tty;
737 tty = get_current_tty();
745 * tty_hung_up_p - was tty hung up
746 * @filp: file pointer of tty
748 * Return true if the tty has been subject to a vhangup or a carrier
752 int tty_hung_up_p(struct file *filp)
754 return (filp->f_op == &hung_up_tty_fops);
757 EXPORT_SYMBOL(tty_hung_up_p);
759 static void session_clear_tty(struct pid *session)
761 struct task_struct *p;
762 do_each_pid_task(session, PIDTYPE_SID, p) {
764 } while_each_pid_task(session, PIDTYPE_SID, p);
768 * disassociate_ctty - disconnect controlling tty
769 * @on_exit: true if exiting so need to "hang up" the session
771 * This function is typically called only by the session leader, when
772 * it wants to disassociate itself from its controlling tty.
774 * It performs the following functions:
775 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
776 * (2) Clears the tty from being controlling the session
777 * (3) Clears the controlling tty for all processes in the
780 * The argument on_exit is set to 1 if called when a process is
781 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
784 * BTM is taken for hysterical raisins, and held when
785 * called from no_tty().
786 * tty_mutex is taken to protect tty
787 * ->siglock is taken to protect ->signal/->sighand
788 * tasklist_lock is taken to walk process list for sessions
789 * ->siglock is taken to protect ->signal/->sighand
792 void disassociate_ctty(int on_exit)
794 struct tty_struct *tty;
796 if (!current->signal->leader)
799 tty = get_current_tty();
801 struct pid *tty_pgrp = get_pid(tty->pgrp);
803 if (tty->driver->type != TTY_DRIVER_TYPE_PTY)
808 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
810 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
813 } else if (on_exit) {
814 struct pid *old_pgrp;
815 spin_lock_irq(¤t->sighand->siglock);
816 old_pgrp = current->signal->tty_old_pgrp;
817 current->signal->tty_old_pgrp = NULL;
818 spin_unlock_irq(¤t->sighand->siglock);
820 kill_pgrp(old_pgrp, SIGHUP, on_exit);
821 kill_pgrp(old_pgrp, SIGCONT, on_exit);
827 spin_lock_irq(¤t->sighand->siglock);
828 put_pid(current->signal->tty_old_pgrp);
829 current->signal->tty_old_pgrp = NULL;
830 spin_unlock_irq(¤t->sighand->siglock);
832 tty = get_current_tty();
835 spin_lock_irqsave(&tty->ctrl_lock, flags);
836 put_pid(tty->session);
840 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
843 #ifdef TTY_DEBUG_HANGUP
844 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
849 /* Now clear signal->tty under the lock */
850 read_lock(&tasklist_lock);
851 session_clear_tty(task_session(current));
852 read_unlock(&tasklist_lock);
857 * no_tty - Ensure the current process does not have a controlling tty
861 /* FIXME: Review locking here. The tty_lock never covered any race
862 between a new association and proc_clear_tty but possible we need
863 to protect against this anyway */
864 struct task_struct *tsk = current;
865 disassociate_ctty(0);
871 * stop_tty - propagate flow control
874 * Perform flow control to the driver. For PTY/TTY pairs we
875 * must also propagate the TIOCKPKT status. May be called
876 * on an already stopped device and will not re-call the driver
879 * This functionality is used by both the line disciplines for
880 * halting incoming flow and by the driver. It may therefore be
881 * called from any context, may be under the tty atomic_write_lock
885 * Uses the tty control lock internally
888 void stop_tty(struct tty_struct *tty)
891 spin_lock_irqsave(&tty->ctrl_lock, flags);
893 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
897 if (tty->link && tty->link->packet) {
898 tty->ctrl_status &= ~TIOCPKT_START;
899 tty->ctrl_status |= TIOCPKT_STOP;
900 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
902 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
904 (tty->ops->stop)(tty);
907 EXPORT_SYMBOL(stop_tty);
910 * start_tty - propagate flow control
913 * Start a tty that has been stopped if at all possible. Perform
914 * any necessary wakeups and propagate the TIOCPKT status. If this
915 * is the tty was previous stopped and is being started then the
916 * driver start method is invoked and the line discipline woken.
922 void start_tty(struct tty_struct *tty)
925 spin_lock_irqsave(&tty->ctrl_lock, flags);
926 if (!tty->stopped || tty->flow_stopped) {
927 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
931 if (tty->link && tty->link->packet) {
932 tty->ctrl_status &= ~TIOCPKT_STOP;
933 tty->ctrl_status |= TIOCPKT_START;
934 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
936 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
938 (tty->ops->start)(tty);
939 /* If we have a running line discipline it may need kicking */
943 EXPORT_SYMBOL(start_tty);
946 * tty_read - read method for tty device files
947 * @file: pointer to tty file
949 * @count: size of user buffer
952 * Perform the read system call function on this terminal device. Checks
953 * for hung up devices before calling the line discipline method.
956 * Locks the line discipline internally while needed. Multiple
957 * read calls may be outstanding in parallel.
960 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
964 struct inode *inode = file->f_path.dentry->d_inode;
965 struct tty_struct *tty = file_tty(file);
966 struct tty_ldisc *ld;
968 if (tty_paranoia_check(tty, inode, "tty_read"))
970 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
973 /* We want to wait for the line discipline to sort out in this
975 ld = tty_ldisc_ref_wait(tty);
977 i = (ld->ops->read)(tty, file, buf, count);
982 inode->i_atime = current_fs_time(inode->i_sb);
986 void tty_write_unlock(struct tty_struct *tty)
987 __releases(&tty->atomic_write_lock)
989 mutex_unlock(&tty->atomic_write_lock);
990 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
993 int tty_write_lock(struct tty_struct *tty, int ndelay)
994 __acquires(&tty->atomic_write_lock)
996 if (!mutex_trylock(&tty->atomic_write_lock)) {
999 if (mutex_lock_interruptible(&tty->atomic_write_lock))
1000 return -ERESTARTSYS;
1006 * Split writes up in sane blocksizes to avoid
1007 * denial-of-service type attacks
1009 static inline ssize_t do_tty_write(
1010 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1011 struct tty_struct *tty,
1013 const char __user *buf,
1016 ssize_t ret, written = 0;
1019 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1024 * We chunk up writes into a temporary buffer. This
1025 * simplifies low-level drivers immensely, since they
1026 * don't have locking issues and user mode accesses.
1028 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1031 * The default chunk-size is 2kB, because the NTTY
1032 * layer has problems with bigger chunks. It will
1033 * claim to be able to handle more characters than
1036 * FIXME: This can probably go away now except that 64K chunks
1037 * are too likely to fail unless switched to vmalloc...
1040 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1045 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1046 if (tty->write_cnt < chunk) {
1047 unsigned char *buf_chunk;
1052 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1057 kfree(tty->write_buf);
1058 tty->write_cnt = chunk;
1059 tty->write_buf = buf_chunk;
1062 /* Do the write .. */
1064 size_t size = count;
1068 if (copy_from_user(tty->write_buf, buf, size))
1070 ret = write(tty, file, tty->write_buf, size);
1079 if (signal_pending(current))
1084 struct inode *inode = file->f_path.dentry->d_inode;
1085 inode->i_mtime = current_fs_time(inode->i_sb);
1089 tty_write_unlock(tty);
1094 * tty_write_message - write a message to a certain tty, not just the console.
1095 * @tty: the destination tty_struct
1096 * @msg: the message to write
1098 * This is used for messages that need to be redirected to a specific tty.
1099 * We don't put it into the syslog queue right now maybe in the future if
1102 * We must still hold the BTM and test the CLOSING flag for the moment.
1105 void tty_write_message(struct tty_struct *tty, char *msg)
1108 mutex_lock(&tty->atomic_write_lock);
1110 if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
1112 tty->ops->write(tty, msg, strlen(msg));
1115 tty_write_unlock(tty);
1122 * tty_write - write method for tty device file
1123 * @file: tty file pointer
1124 * @buf: user data to write
1125 * @count: bytes to write
1128 * Write data to a tty device via the line discipline.
1131 * Locks the line discipline as required
1132 * Writes to the tty driver are serialized by the atomic_write_lock
1133 * and are then processed in chunks to the device. The line discipline
1134 * write method will not be invoked in parallel for each device.
1137 static ssize_t tty_write(struct file *file, const char __user *buf,
1138 size_t count, loff_t *ppos)
1140 struct inode *inode = file->f_path.dentry->d_inode;
1141 struct tty_struct *tty = file_tty(file);
1142 struct tty_ldisc *ld;
1145 if (tty_paranoia_check(tty, inode, "tty_write"))
1147 if (!tty || !tty->ops->write ||
1148 (test_bit(TTY_IO_ERROR, &tty->flags)))
1150 /* Short term debug to catch buggy drivers */
1151 if (tty->ops->write_room == NULL)
1152 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1154 ld = tty_ldisc_ref_wait(tty);
1155 if (!ld->ops->write)
1158 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1159 tty_ldisc_deref(ld);
1163 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1164 size_t count, loff_t *ppos)
1166 struct file *p = NULL;
1168 spin_lock(&redirect_lock);
1173 spin_unlock(&redirect_lock);
1177 res = vfs_write(p, buf, count, &p->f_pos);
1181 return tty_write(file, buf, count, ppos);
1184 static char ptychar[] = "pqrstuvwxyzabcde";
1187 * pty_line_name - generate name for a pty
1188 * @driver: the tty driver in use
1189 * @index: the minor number
1190 * @p: output buffer of at least 6 bytes
1192 * Generate a name from a driver reference and write it to the output
1197 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1199 int i = index + driver->name_base;
1200 /* ->name is initialized to "ttyp", but "tty" is expected */
1201 sprintf(p, "%s%c%x",
1202 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1203 ptychar[i >> 4 & 0xf], i & 0xf);
1207 * tty_line_name - generate name for a tty
1208 * @driver: the tty driver in use
1209 * @index: the minor number
1210 * @p: output buffer of at least 7 bytes
1212 * Generate a name from a driver reference and write it to the output
1217 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1219 sprintf(p, "%s%d", driver->name, index + driver->name_base);
1223 * tty_driver_lookup_tty() - find an existing tty, if any
1224 * @driver: the driver for the tty
1225 * @idx: the minor number
1227 * Return the tty, if found or ERR_PTR() otherwise.
1229 * Locking: tty_mutex must be held. If tty is found, the mutex must
1230 * be held until the 'fast-open' is also done. Will change once we
1231 * have refcounting in the driver and per driver locking
1233 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1234 struct inode *inode, int idx)
1236 if (driver->ops->lookup)
1237 return driver->ops->lookup(driver, inode, idx);
1239 return driver->ttys[idx];
1243 * tty_init_termios - helper for termios setup
1244 * @tty: the tty to set up
1246 * Initialise the termios structures for this tty. Thus runs under
1247 * the tty_mutex currently so we can be relaxed about ordering.
1250 int tty_init_termios(struct tty_struct *tty)
1252 struct ktermios *tp;
1253 int idx = tty->index;
1255 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1256 tty->termios = tty->driver->init_termios;
1258 /* Check for lazy saved data */
1259 tp = tty->driver->termios[idx];
1263 tty->termios = tty->driver->init_termios;
1265 /* Compatibility until drivers always set this */
1266 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1267 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1270 EXPORT_SYMBOL_GPL(tty_init_termios);
1272 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1274 int ret = tty_init_termios(tty);
1278 tty_driver_kref_get(driver);
1280 driver->ttys[tty->index] = tty;
1283 EXPORT_SYMBOL_GPL(tty_standard_install);
1286 * tty_driver_install_tty() - install a tty entry in the driver
1287 * @driver: the driver for the tty
1290 * Install a tty object into the driver tables. The tty->index field
1291 * will be set by the time this is called. This method is responsible
1292 * for ensuring any need additional structures are allocated and
1295 * Locking: tty_mutex for now
1297 static int tty_driver_install_tty(struct tty_driver *driver,
1298 struct tty_struct *tty)
1300 return driver->ops->install ? driver->ops->install(driver, tty) :
1301 tty_standard_install(driver, tty);
1305 * tty_driver_remove_tty() - remove a tty from the driver tables
1306 * @driver: the driver for the tty
1307 * @idx: the minor number
1309 * Remvoe a tty object from the driver tables. The tty->index field
1310 * will be set by the time this is called.
1312 * Locking: tty_mutex for now
1314 void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1316 if (driver->ops->remove)
1317 driver->ops->remove(driver, tty);
1319 driver->ttys[tty->index] = NULL;
1323 * tty_reopen() - fast re-open of an open tty
1324 * @tty - the tty to open
1326 * Return 0 on success, -errno on error.
1328 * Locking: tty_mutex must be held from the time the tty was found
1329 * till this open completes.
1331 static int tty_reopen(struct tty_struct *tty)
1333 struct tty_driver *driver = tty->driver;
1335 if (test_bit(TTY_CLOSING, &tty->flags) ||
1336 test_bit(TTY_HUPPING, &tty->flags) ||
1337 test_bit(TTY_LDISC_CHANGING, &tty->flags))
1340 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1341 driver->subtype == PTY_TYPE_MASTER) {
1343 * special case for PTY masters: only one open permitted,
1344 * and the slave side open count is incremented as well.
1353 mutex_lock(&tty->ldisc_mutex);
1354 WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1355 mutex_unlock(&tty->ldisc_mutex);
1361 * tty_init_dev - initialise a tty device
1362 * @driver: tty driver we are opening a device on
1363 * @idx: device index
1364 * @ret_tty: returned tty structure
1366 * Prepare a tty device. This may not be a "new" clean device but
1367 * could also be an active device. The pty drivers require special
1368 * handling because of this.
1371 * The function is called under the tty_mutex, which
1372 * protects us from the tty struct or driver itself going away.
1374 * On exit the tty device has the line discipline attached and
1375 * a reference count of 1. If a pair was created for pty/tty use
1376 * and the other was a pty master then it too has a reference count of 1.
1378 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1379 * failed open. The new code protects the open with a mutex, so it's
1380 * really quite straightforward. The mutex locking can probably be
1381 * relaxed for the (most common) case of reopening a tty.
1384 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1386 struct tty_struct *tty;
1390 * First time open is complex, especially for PTY devices.
1391 * This code guarantees that either everything succeeds and the
1392 * TTY is ready for operation, or else the table slots are vacated
1393 * and the allocated memory released. (Except that the termios
1394 * and locked termios may be retained.)
1397 if (!try_module_get(driver->owner))
1398 return ERR_PTR(-ENODEV);
1400 tty = alloc_tty_struct();
1403 goto err_module_put;
1405 initialize_tty_struct(tty, driver, idx);
1408 retval = tty_driver_install_tty(driver, tty);
1410 goto err_deinit_tty;
1413 tty->port = driver->ports[idx];
1416 * Structures all installed ... call the ldisc open routines.
1417 * If we fail here just call release_tty to clean up. No need
1418 * to decrement the use counts, as release_tty doesn't care.
1420 retval = tty_ldisc_setup(tty, tty->link);
1422 goto err_release_tty;
1423 /* Return the tty locked so that it cannot vanish under the caller */
1428 deinitialize_tty_struct(tty);
1429 free_tty_struct(tty);
1431 module_put(driver->owner);
1432 return ERR_PTR(retval);
1434 /* call the tty release_tty routine to clean out this slot */
1437 printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, "
1438 "clearing slot %d\n", idx);
1439 release_tty(tty, idx);
1440 return ERR_PTR(retval);
1443 void tty_free_termios(struct tty_struct *tty)
1445 struct ktermios *tp;
1446 int idx = tty->index;
1448 /* If the port is going to reset then it has no termios to save */
1449 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1452 /* Stash the termios data */
1453 tp = tty->driver->termios[idx];
1455 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1457 pr_warn("tty: no memory to save termios state.\n");
1460 tty->driver->termios[idx] = tp;
1464 EXPORT_SYMBOL(tty_free_termios);
1468 * release_one_tty - release tty structure memory
1469 * @kref: kref of tty we are obliterating
1471 * Releases memory associated with a tty structure, and clears out the
1472 * driver table slots. This function is called when a device is no longer
1473 * in use. It also gets called when setup of a device fails.
1476 * takes the file list lock internally when working on the list
1477 * of ttys that the driver keeps.
1479 * This method gets called from a work queue so that the driver private
1480 * cleanup ops can sleep (needed for USB at least)
1482 static void release_one_tty(struct work_struct *work)
1484 struct tty_struct *tty =
1485 container_of(work, struct tty_struct, hangup_work);
1486 struct tty_driver *driver = tty->driver;
1488 if (tty->ops->cleanup)
1489 tty->ops->cleanup(tty);
1492 tty_driver_kref_put(driver);
1493 module_put(driver->owner);
1495 spin_lock(&tty_files_lock);
1496 list_del_init(&tty->tty_files);
1497 spin_unlock(&tty_files_lock);
1500 put_pid(tty->session);
1501 free_tty_struct(tty);
1504 static void queue_release_one_tty(struct kref *kref)
1506 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1508 /* The hangup queue is now free so we can reuse it rather than
1509 waste a chunk of memory for each port */
1510 INIT_WORK(&tty->hangup_work, release_one_tty);
1511 schedule_work(&tty->hangup_work);
1515 * tty_kref_put - release a tty kref
1518 * Release a reference to a tty device and if need be let the kref
1519 * layer destruct the object for us
1522 void tty_kref_put(struct tty_struct *tty)
1525 kref_put(&tty->kref, queue_release_one_tty);
1527 EXPORT_SYMBOL(tty_kref_put);
1530 * release_tty - release tty structure memory
1532 * Release both @tty and a possible linked partner (think pty pair),
1533 * and decrement the refcount of the backing module.
1537 * takes the file list lock internally when working on the list
1538 * of ttys that the driver keeps.
1541 static void release_tty(struct tty_struct *tty, int idx)
1543 /* This should always be true but check for the moment */
1544 WARN_ON(tty->index != idx);
1545 WARN_ON(!mutex_is_locked(&tty_mutex));
1546 if (tty->ops->shutdown)
1547 tty->ops->shutdown(tty);
1548 tty_free_termios(tty);
1549 tty_driver_remove_tty(tty->driver, tty);
1552 tty_kref_put(tty->link);
1557 * tty_release_checks - check a tty before real release
1558 * @tty: tty to check
1559 * @o_tty: link of @tty (if any)
1560 * @idx: index of the tty
1562 * Performs some paranoid checking before true release of the @tty.
1563 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1565 static int tty_release_checks(struct tty_struct *tty, struct tty_struct *o_tty,
1568 #ifdef TTY_PARANOIA_CHECK
1569 if (idx < 0 || idx >= tty->driver->num) {
1570 printk(KERN_DEBUG "%s: bad idx when trying to free (%s)\n",
1571 __func__, tty->name);
1575 /* not much to check for devpts */
1576 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1579 if (tty != tty->driver->ttys[idx]) {
1580 printk(KERN_DEBUG "%s: driver.table[%d] not tty for (%s)\n",
1581 __func__, idx, tty->name);
1584 if (tty->driver->other) {
1585 if (o_tty != tty->driver->other->ttys[idx]) {
1586 printk(KERN_DEBUG "%s: other->table[%d] not o_tty for (%s)\n",
1587 __func__, idx, tty->name);
1590 if (o_tty->link != tty) {
1591 printk(KERN_DEBUG "%s: bad pty pointers\n", __func__);
1600 * tty_release - vfs callback for close
1601 * @inode: inode of tty
1602 * @filp: file pointer for handle to tty
1604 * Called the last time each file handle is closed that references
1605 * this tty. There may however be several such references.
1608 * Takes bkl. See tty_release_dev
1610 * Even releasing the tty structures is a tricky business.. We have
1611 * to be very careful that the structures are all released at the
1612 * same time, as interrupts might otherwise get the wrong pointers.
1614 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1615 * lead to double frees or releasing memory still in use.
1618 int tty_release(struct inode *inode, struct file *filp)
1620 struct tty_struct *tty = file_tty(filp);
1621 struct tty_struct *o_tty;
1622 int pty_master, tty_closing, o_tty_closing, do_sleep;
1627 if (tty_paranoia_check(tty, inode, __func__))
1631 check_tty_count(tty, __func__);
1633 __tty_fasync(-1, filp, 0);
1636 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1637 tty->driver->subtype == PTY_TYPE_MASTER);
1638 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1639 /* Review: parallel close */
1642 if (tty_release_checks(tty, o_tty, idx)) {
1647 #ifdef TTY_DEBUG_HANGUP
1648 printk(KERN_DEBUG "%s: %s (tty count=%d)...\n", __func__,
1649 tty_name(tty, buf), tty->count);
1652 if (tty->ops->close)
1653 tty->ops->close(tty, filp);
1657 * Sanity check: if tty->count is going to zero, there shouldn't be
1658 * any waiters on tty->read_wait or tty->write_wait. We test the
1659 * wait queues and kick everyone out _before_ actually starting to
1660 * close. This ensures that we won't block while releasing the tty
1663 * The test for the o_tty closing is necessary, since the master and
1664 * slave sides may close in any order. If the slave side closes out
1665 * first, its count will be one, since the master side holds an open.
1666 * Thus this test wouldn't be triggered at the time the slave closes,
1669 * Note that it's possible for the tty to be opened again while we're
1670 * flushing out waiters. By recalculating the closing flags before
1671 * each iteration we avoid any problems.
1674 /* Guard against races with tty->count changes elsewhere and
1675 opens on /dev/tty */
1677 mutex_lock(&tty_mutex);
1678 tty_lock_pair(tty, o_tty);
1679 tty_closing = tty->count <= 1;
1680 o_tty_closing = o_tty &&
1681 (o_tty->count <= (pty_master ? 1 : 0));
1685 if (waitqueue_active(&tty->read_wait)) {
1686 wake_up_poll(&tty->read_wait, POLLIN);
1689 if (waitqueue_active(&tty->write_wait)) {
1690 wake_up_poll(&tty->write_wait, POLLOUT);
1694 if (o_tty_closing) {
1695 if (waitqueue_active(&o_tty->read_wait)) {
1696 wake_up_poll(&o_tty->read_wait, POLLIN);
1699 if (waitqueue_active(&o_tty->write_wait)) {
1700 wake_up_poll(&o_tty->write_wait, POLLOUT);
1707 printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",
1708 __func__, tty_name(tty, buf));
1709 tty_unlock_pair(tty, o_tty);
1710 mutex_unlock(&tty_mutex);
1715 * The closing flags are now consistent with the open counts on
1716 * both sides, and we've completed the last operation that could
1717 * block, so it's safe to proceed with closing.
1719 * We must *not* drop the tty_mutex until we ensure that a further
1720 * entry into tty_open can not pick up this tty.
1723 if (--o_tty->count < 0) {
1724 printk(KERN_WARNING "%s: bad pty slave count (%d) for %s\n",
1725 __func__, o_tty->count, tty_name(o_tty, buf));
1729 if (--tty->count < 0) {
1730 printk(KERN_WARNING "%s: bad tty->count (%d) for %s\n",
1731 __func__, tty->count, tty_name(tty, buf));
1736 * We've decremented tty->count, so we need to remove this file
1737 * descriptor off the tty->tty_files list; this serves two
1739 * - check_tty_count sees the correct number of file descriptors
1740 * associated with this tty.
1741 * - do_tty_hangup no longer sees this file descriptor as
1742 * something that needs to be handled for hangups.
1747 * Perform some housekeeping before deciding whether to return.
1749 * Set the TTY_CLOSING flag if this was the last open. In the
1750 * case of a pty we may have to wait around for the other side
1751 * to close, and TTY_CLOSING makes sure we can't be reopened.
1754 set_bit(TTY_CLOSING, &tty->flags);
1756 set_bit(TTY_CLOSING, &o_tty->flags);
1759 * If _either_ side is closing, make sure there aren't any
1760 * processes that still think tty or o_tty is their controlling
1763 if (tty_closing || o_tty_closing) {
1764 read_lock(&tasklist_lock);
1765 session_clear_tty(tty->session);
1767 session_clear_tty(o_tty->session);
1768 read_unlock(&tasklist_lock);
1771 mutex_unlock(&tty_mutex);
1772 tty_unlock_pair(tty, o_tty);
1773 /* At this point the TTY_CLOSING flag should ensure a dead tty
1774 cannot be re-opened by a racing opener */
1776 /* check whether both sides are closing ... */
1777 if (!tty_closing || (o_tty && !o_tty_closing))
1780 #ifdef TTY_DEBUG_HANGUP
1781 printk(KERN_DEBUG "%s: freeing tty structure...\n", __func__);
1784 * Ask the line discipline code to release its structures
1786 tty_ldisc_release(tty, o_tty);
1788 * The release_tty function takes care of the details of clearing
1789 * the slots and preserving the termios structure. The tty_unlock_pair
1790 * should be safe as we keep a kref while the tty is locked (so the
1791 * unlock never unlocks a freed tty).
1793 mutex_lock(&tty_mutex);
1794 release_tty(tty, idx);
1795 mutex_unlock(&tty_mutex);
1797 /* Make this pty number available for reallocation */
1799 devpts_kill_index(inode, idx);
1804 * tty_open_current_tty - get tty of current task for open
1805 * @device: device number
1806 * @filp: file pointer to tty
1807 * @return: tty of the current task iff @device is /dev/tty
1809 * We cannot return driver and index like for the other nodes because
1810 * devpts will not work then. It expects inodes to be from devpts FS.
1812 * We need to move to returning a refcounted object from all the lookup
1813 * paths including this one.
1815 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1817 struct tty_struct *tty;
1819 if (device != MKDEV(TTYAUX_MAJOR, 0))
1822 tty = get_current_tty();
1824 return ERR_PTR(-ENXIO);
1826 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1829 /* FIXME: we put a reference and return a TTY! */
1830 /* This is only safe because the caller holds tty_mutex */
1835 * tty_lookup_driver - lookup a tty driver for a given device file
1836 * @device: device number
1837 * @filp: file pointer to tty
1838 * @noctty: set if the device should not become a controlling tty
1839 * @index: index for the device in the @return driver
1840 * @return: driver for this inode (with increased refcount)
1842 * If @return is not erroneous, the caller is responsible to decrement the
1843 * refcount by tty_driver_kref_put.
1845 * Locking: tty_mutex protects get_tty_driver
1847 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1848 int *noctty, int *index)
1850 struct tty_driver *driver;
1854 case MKDEV(TTY_MAJOR, 0): {
1855 extern struct tty_driver *console_driver;
1856 driver = tty_driver_kref_get(console_driver);
1857 *index = fg_console;
1862 case MKDEV(TTYAUX_MAJOR, 1): {
1863 struct tty_driver *console_driver = console_device(index);
1864 if (console_driver) {
1865 driver = tty_driver_kref_get(console_driver);
1867 /* Don't let /dev/console block */
1868 filp->f_flags |= O_NONBLOCK;
1873 return ERR_PTR(-ENODEV);
1876 driver = get_tty_driver(device, index);
1878 return ERR_PTR(-ENODEV);
1885 * tty_open - open a tty device
1886 * @inode: inode of device file
1887 * @filp: file pointer to tty
1889 * tty_open and tty_release keep up the tty count that contains the
1890 * number of opens done on a tty. We cannot use the inode-count, as
1891 * different inodes might point to the same tty.
1893 * Open-counting is needed for pty masters, as well as for keeping
1894 * track of serial lines: DTR is dropped when the last close happens.
1895 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1897 * The termios state of a pty is reset on first open so that
1898 * settings don't persist across reuse.
1900 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
1901 * tty->count should protect the rest.
1902 * ->siglock protects ->signal/->sighand
1904 * Note: the tty_unlock/lock cases without a ref are only safe due to
1908 static int tty_open(struct inode *inode, struct file *filp)
1910 struct tty_struct *tty;
1912 struct tty_driver *driver = NULL;
1914 dev_t device = inode->i_rdev;
1915 unsigned saved_flags = filp->f_flags;
1917 nonseekable_open(inode, filp);
1920 retval = tty_alloc_file(filp);
1924 noctty = filp->f_flags & O_NOCTTY;
1928 mutex_lock(&tty_mutex);
1929 /* This is protected by the tty_mutex */
1930 tty = tty_open_current_tty(device, filp);
1932 retval = PTR_ERR(tty);
1935 driver = tty_lookup_driver(device, filp, &noctty, &index);
1936 if (IS_ERR(driver)) {
1937 retval = PTR_ERR(driver);
1941 /* check whether we're reopening an existing tty */
1942 tty = tty_driver_lookup_tty(driver, inode, index);
1944 retval = PTR_ERR(tty);
1951 retval = tty_reopen(tty);
1954 tty = ERR_PTR(retval);
1956 } else /* Returns with the tty_lock held for now */
1957 tty = tty_init_dev(driver, index);
1959 mutex_unlock(&tty_mutex);
1961 tty_driver_kref_put(driver);
1963 retval = PTR_ERR(tty);
1967 tty_add_file(tty, filp);
1969 check_tty_count(tty, __func__);
1970 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1971 tty->driver->subtype == PTY_TYPE_MASTER)
1973 #ifdef TTY_DEBUG_HANGUP
1974 printk(KERN_DEBUG "%s: opening %s...\n", __func__, tty->name);
1977 retval = tty->ops->open(tty, filp);
1980 filp->f_flags = saved_flags;
1982 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
1983 !capable(CAP_SYS_ADMIN))
1987 #ifdef TTY_DEBUG_HANGUP
1988 printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,
1991 tty_unlock(tty); /* need to call tty_release without BTM */
1992 tty_release(inode, filp);
1993 if (retval != -ERESTARTSYS)
1996 if (signal_pending(current))
2001 * Need to reset f_op in case a hangup happened.
2003 if (filp->f_op == &hung_up_tty_fops)
2004 filp->f_op = &tty_fops;
2010 mutex_lock(&tty_mutex);
2012 spin_lock_irq(¤t->sighand->siglock);
2014 current->signal->leader &&
2015 !current->signal->tty &&
2016 tty->session == NULL)
2017 __proc_set_tty(current, tty);
2018 spin_unlock_irq(¤t->sighand->siglock);
2020 mutex_unlock(&tty_mutex);
2023 mutex_unlock(&tty_mutex);
2024 /* after locks to avoid deadlock */
2025 if (!IS_ERR_OR_NULL(driver))
2026 tty_driver_kref_put(driver);
2028 tty_free_file(filp);
2035 * tty_poll - check tty status
2036 * @filp: file being polled
2037 * @wait: poll wait structures to update
2039 * Call the line discipline polling method to obtain the poll
2040 * status of the device.
2042 * Locking: locks called line discipline but ldisc poll method
2043 * may be re-entered freely by other callers.
2046 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2048 struct tty_struct *tty = file_tty(filp);
2049 struct tty_ldisc *ld;
2052 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2055 ld = tty_ldisc_ref_wait(tty);
2057 ret = (ld->ops->poll)(tty, filp, wait);
2058 tty_ldisc_deref(ld);
2062 static int __tty_fasync(int fd, struct file *filp, int on)
2064 struct tty_struct *tty = file_tty(filp);
2065 unsigned long flags;
2068 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2071 retval = fasync_helper(fd, filp, on, &tty->fasync);
2078 if (!waitqueue_active(&tty->read_wait))
2079 tty->minimum_to_wake = 1;
2080 spin_lock_irqsave(&tty->ctrl_lock, flags);
2083 type = PIDTYPE_PGID;
2085 pid = task_pid(current);
2089 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2090 retval = __f_setown(filp, pid, type, 0);
2095 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2096 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2103 static int tty_fasync(int fd, struct file *filp, int on)
2105 struct tty_struct *tty = file_tty(filp);
2109 retval = __tty_fasync(fd, filp, on);
2116 * tiocsti - fake input character
2117 * @tty: tty to fake input into
2118 * @p: pointer to character
2120 * Fake input to a tty device. Does the necessary locking and
2123 * FIXME: does not honour flow control ??
2126 * Called functions take tty_ldisc_lock
2127 * current->signal->tty check is safe without locks
2129 * FIXME: may race normal receive processing
2132 static int tiocsti(struct tty_struct *tty, char __user *p)
2135 struct tty_ldisc *ld;
2137 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2139 if (get_user(ch, p))
2141 tty_audit_tiocsti(tty, ch);
2142 ld = tty_ldisc_ref_wait(tty);
2143 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2144 tty_ldisc_deref(ld);
2149 * tiocgwinsz - implement window query ioctl
2151 * @arg: user buffer for result
2153 * Copies the kernel idea of the window size into the user buffer.
2155 * Locking: tty->termios_mutex is taken to ensure the winsize data
2159 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2163 mutex_lock(&tty->termios_mutex);
2164 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2165 mutex_unlock(&tty->termios_mutex);
2167 return err ? -EFAULT: 0;
2171 * tty_do_resize - resize event
2172 * @tty: tty being resized
2173 * @rows: rows (character)
2174 * @cols: cols (character)
2176 * Update the termios variables and send the necessary signals to
2177 * peform a terminal resize correctly
2180 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2183 unsigned long flags;
2186 mutex_lock(&tty->termios_mutex);
2187 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2189 /* Get the PID values and reference them so we can
2190 avoid holding the tty ctrl lock while sending signals */
2191 spin_lock_irqsave(&tty->ctrl_lock, flags);
2192 pgrp = get_pid(tty->pgrp);
2193 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2196 kill_pgrp(pgrp, SIGWINCH, 1);
2201 mutex_unlock(&tty->termios_mutex);
2206 * tiocswinsz - implement window size set ioctl
2207 * @tty; tty side of tty
2208 * @arg: user buffer for result
2210 * Copies the user idea of the window size to the kernel. Traditionally
2211 * this is just advisory information but for the Linux console it
2212 * actually has driver level meaning and triggers a VC resize.
2215 * Driver dependent. The default do_resize method takes the
2216 * tty termios mutex and ctrl_lock. The console takes its own lock
2217 * then calls into the default method.
2220 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2222 struct winsize tmp_ws;
2223 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2226 if (tty->ops->resize)
2227 return tty->ops->resize(tty, &tmp_ws);
2229 return tty_do_resize(tty, &tmp_ws);
2233 * tioccons - allow admin to move logical console
2234 * @file: the file to become console
2236 * Allow the administrator to move the redirected console device
2238 * Locking: uses redirect_lock to guard the redirect information
2241 static int tioccons(struct file *file)
2243 if (!capable(CAP_SYS_ADMIN))
2245 if (file->f_op->write == redirected_tty_write) {
2247 spin_lock(&redirect_lock);
2250 spin_unlock(&redirect_lock);
2255 spin_lock(&redirect_lock);
2257 spin_unlock(&redirect_lock);
2262 spin_unlock(&redirect_lock);
2267 * fionbio - non blocking ioctl
2268 * @file: file to set blocking value
2269 * @p: user parameter
2271 * Historical tty interfaces had a blocking control ioctl before
2272 * the generic functionality existed. This piece of history is preserved
2273 * in the expected tty API of posix OS's.
2275 * Locking: none, the open file handle ensures it won't go away.
2278 static int fionbio(struct file *file, int __user *p)
2282 if (get_user(nonblock, p))
2285 spin_lock(&file->f_lock);
2287 file->f_flags |= O_NONBLOCK;
2289 file->f_flags &= ~O_NONBLOCK;
2290 spin_unlock(&file->f_lock);
2295 * tiocsctty - set controlling tty
2296 * @tty: tty structure
2297 * @arg: user argument
2299 * This ioctl is used to manage job control. It permits a session
2300 * leader to set this tty as the controlling tty for the session.
2303 * Takes tty_mutex() to protect tty instance
2304 * Takes tasklist_lock internally to walk sessions
2305 * Takes ->siglock() when updating signal->tty
2308 static int tiocsctty(struct tty_struct *tty, int arg)
2311 if (current->signal->leader && (task_session(current) == tty->session))
2314 mutex_lock(&tty_mutex);
2316 * The process must be a session leader and
2317 * not have a controlling tty already.
2319 if (!current->signal->leader || current->signal->tty) {
2326 * This tty is already the controlling
2327 * tty for another session group!
2329 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2333 read_lock(&tasklist_lock);
2334 session_clear_tty(tty->session);
2335 read_unlock(&tasklist_lock);
2341 proc_set_tty(current, tty);
2343 mutex_unlock(&tty_mutex);
2348 * tty_get_pgrp - return a ref counted pgrp pid
2351 * Returns a refcounted instance of the pid struct for the process
2352 * group controlling the tty.
2355 struct pid *tty_get_pgrp(struct tty_struct *tty)
2357 unsigned long flags;
2360 spin_lock_irqsave(&tty->ctrl_lock, flags);
2361 pgrp = get_pid(tty->pgrp);
2362 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2366 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2369 * tiocgpgrp - get process group
2370 * @tty: tty passed by user
2371 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2374 * Obtain the process group of the tty. If there is no process group
2377 * Locking: none. Reference to current->signal->tty is safe.
2380 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2385 * (tty == real_tty) is a cheap way of
2386 * testing if the tty is NOT a master pty.
2388 if (tty == real_tty && current->signal->tty != real_tty)
2390 pid = tty_get_pgrp(real_tty);
2391 ret = put_user(pid_vnr(pid), p);
2397 * tiocspgrp - attempt to set process group
2398 * @tty: tty passed by user
2399 * @real_tty: tty side device matching tty passed by user
2402 * Set the process group of the tty to the session passed. Only
2403 * permitted where the tty session is our session.
2405 * Locking: RCU, ctrl lock
2408 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2412 int retval = tty_check_change(real_tty);
2413 unsigned long flags;
2419 if (!current->signal->tty ||
2420 (current->signal->tty != real_tty) ||
2421 (real_tty->session != task_session(current)))
2423 if (get_user(pgrp_nr, p))
2428 pgrp = find_vpid(pgrp_nr);
2433 if (session_of_pgrp(pgrp) != task_session(current))
2436 spin_lock_irqsave(&tty->ctrl_lock, flags);
2437 put_pid(real_tty->pgrp);
2438 real_tty->pgrp = get_pid(pgrp);
2439 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2446 * tiocgsid - get session id
2447 * @tty: tty passed by user
2448 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2449 * @p: pointer to returned session id
2451 * Obtain the session id of the tty. If there is no session
2454 * Locking: none. Reference to current->signal->tty is safe.
2457 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2460 * (tty == real_tty) is a cheap way of
2461 * testing if the tty is NOT a master pty.
2463 if (tty == real_tty && current->signal->tty != real_tty)
2465 if (!real_tty->session)
2467 return put_user(pid_vnr(real_tty->session), p);
2471 * tiocsetd - set line discipline
2473 * @p: pointer to user data
2475 * Set the line discipline according to user request.
2477 * Locking: see tty_set_ldisc, this function is just a helper
2480 static int tiocsetd(struct tty_struct *tty, int __user *p)
2485 if (get_user(ldisc, p))
2488 ret = tty_set_ldisc(tty, ldisc);
2494 * send_break - performed time break
2495 * @tty: device to break on
2496 * @duration: timeout in mS
2498 * Perform a timed break on hardware that lacks its own driver level
2499 * timed break functionality.
2502 * atomic_write_lock serializes
2506 static int send_break(struct tty_struct *tty, unsigned int duration)
2510 if (tty->ops->break_ctl == NULL)
2513 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2514 retval = tty->ops->break_ctl(tty, duration);
2516 /* Do the work ourselves */
2517 if (tty_write_lock(tty, 0) < 0)
2519 retval = tty->ops->break_ctl(tty, -1);
2522 if (!signal_pending(current))
2523 msleep_interruptible(duration);
2524 retval = tty->ops->break_ctl(tty, 0);
2526 tty_write_unlock(tty);
2527 if (signal_pending(current))
2534 * tty_tiocmget - get modem status
2536 * @file: user file pointer
2537 * @p: pointer to result
2539 * Obtain the modem status bits from the tty driver if the feature
2540 * is supported. Return -EINVAL if it is not available.
2542 * Locking: none (up to the driver)
2545 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2547 int retval = -EINVAL;
2549 if (tty->ops->tiocmget) {
2550 retval = tty->ops->tiocmget(tty);
2553 retval = put_user(retval, p);
2559 * tty_tiocmset - set modem status
2561 * @cmd: command - clear bits, set bits or set all
2562 * @p: pointer to desired bits
2564 * Set the modem status bits from the tty driver if the feature
2565 * is supported. Return -EINVAL if it is not available.
2567 * Locking: none (up to the driver)
2570 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2574 unsigned int set, clear, val;
2576 if (tty->ops->tiocmset == NULL)
2579 retval = get_user(val, p);
2595 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2596 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2597 return tty->ops->tiocmset(tty, set, clear);
2600 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2602 int retval = -EINVAL;
2603 struct serial_icounter_struct icount;
2604 memset(&icount, 0, sizeof(icount));
2605 if (tty->ops->get_icount)
2606 retval = tty->ops->get_icount(tty, &icount);
2609 if (copy_to_user(arg, &icount, sizeof(icount)))
2614 struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2616 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2617 tty->driver->subtype == PTY_TYPE_MASTER)
2621 EXPORT_SYMBOL(tty_pair_get_tty);
2623 struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)
2625 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2626 tty->driver->subtype == PTY_TYPE_MASTER)
2630 EXPORT_SYMBOL(tty_pair_get_pty);
2633 * Split this up, as gcc can choke on it otherwise..
2635 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2637 struct tty_struct *tty = file_tty(file);
2638 struct tty_struct *real_tty;
2639 void __user *p = (void __user *)arg;
2641 struct tty_ldisc *ld;
2642 struct inode *inode = file->f_dentry->d_inode;
2644 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2647 real_tty = tty_pair_get_tty(tty);
2650 * Factor out some common prep work
2658 retval = tty_check_change(tty);
2661 if (cmd != TIOCCBRK) {
2662 tty_wait_until_sent(tty, 0);
2663 if (signal_pending(current))
2674 return tiocsti(tty, p);
2676 return tiocgwinsz(real_tty, p);
2678 return tiocswinsz(real_tty, p);
2680 return real_tty != tty ? -EINVAL : tioccons(file);
2682 return fionbio(file, p);
2684 set_bit(TTY_EXCLUSIVE, &tty->flags);
2687 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2690 if (current->signal->tty != tty)
2695 return tiocsctty(tty, arg);
2697 return tiocgpgrp(tty, real_tty, p);
2699 return tiocspgrp(tty, real_tty, p);
2701 return tiocgsid(tty, real_tty, p);
2703 return put_user(tty->ldisc->ops->num, (int __user *)p);
2705 return tiocsetd(tty, p);
2707 if (!capable(CAP_SYS_ADMIN))
2713 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2714 return put_user(ret, (unsigned int __user *)p);
2719 case TIOCSBRK: /* Turn break on, unconditionally */
2720 if (tty->ops->break_ctl)
2721 return tty->ops->break_ctl(tty, -1);
2723 case TIOCCBRK: /* Turn break off, unconditionally */
2724 if (tty->ops->break_ctl)
2725 return tty->ops->break_ctl(tty, 0);
2727 case TCSBRK: /* SVID version: non-zero arg --> no break */
2728 /* non-zero arg means wait for all output data
2729 * to be sent (performed above) but don't send break.
2730 * This is used by the tcdrain() termios function.
2733 return send_break(tty, 250);
2735 case TCSBRKP: /* support for POSIX tcsendbreak() */
2736 return send_break(tty, arg ? arg*100 : 250);
2739 return tty_tiocmget(tty, p);
2743 return tty_tiocmset(tty, cmd, p);
2745 retval = tty_tiocgicount(tty, p);
2746 /* For the moment allow fall through to the old method */
2747 if (retval != -EINVAL)
2754 /* flush tty buffer and allow ldisc to process ioctl */
2755 tty_buffer_flush(tty);
2760 if (tty->ops->ioctl) {
2761 retval = (tty->ops->ioctl)(tty, cmd, arg);
2762 if (retval != -ENOIOCTLCMD)
2765 ld = tty_ldisc_ref_wait(tty);
2767 if (ld->ops->ioctl) {
2768 retval = ld->ops->ioctl(tty, file, cmd, arg);
2769 if (retval == -ENOIOCTLCMD)
2772 tty_ldisc_deref(ld);
2776 #ifdef CONFIG_COMPAT
2777 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2780 struct inode *inode = file->f_dentry->d_inode;
2781 struct tty_struct *tty = file_tty(file);
2782 struct tty_ldisc *ld;
2783 int retval = -ENOIOCTLCMD;
2785 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2788 if (tty->ops->compat_ioctl) {
2789 retval = (tty->ops->compat_ioctl)(tty, cmd, arg);
2790 if (retval != -ENOIOCTLCMD)
2794 ld = tty_ldisc_ref_wait(tty);
2795 if (ld->ops->compat_ioctl)
2796 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2798 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
2799 tty_ldisc_deref(ld);
2806 * This implements the "Secure Attention Key" --- the idea is to
2807 * prevent trojan horses by killing all processes associated with this
2808 * tty when the user hits the "Secure Attention Key". Required for
2809 * super-paranoid applications --- see the Orange Book for more details.
2811 * This code could be nicer; ideally it should send a HUP, wait a few
2812 * seconds, then send a INT, and then a KILL signal. But you then
2813 * have to coordinate with the init process, since all processes associated
2814 * with the current tty must be dead before the new getty is allowed
2817 * Now, if it would be correct ;-/ The current code has a nasty hole -
2818 * it doesn't catch files in flight. We may send the descriptor to ourselves
2819 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2821 * Nasty bug: do_SAK is being called in interrupt context. This can
2822 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2824 void __do_SAK(struct tty_struct *tty)
2829 struct task_struct *g, *p;
2830 struct pid *session;
2833 struct fdtable *fdt;
2837 session = tty->session;
2839 tty_ldisc_flush(tty);
2841 tty_driver_flush_buffer(tty);
2843 read_lock(&tasklist_lock);
2844 /* Kill the entire session */
2845 do_each_pid_task(session, PIDTYPE_SID, p) {
2846 printk(KERN_NOTICE "SAK: killed process %d"
2847 " (%s): task_session(p)==tty->session\n",
2848 task_pid_nr(p), p->comm);
2849 send_sig(SIGKILL, p, 1);
2850 } while_each_pid_task(session, PIDTYPE_SID, p);
2851 /* Now kill any processes that happen to have the
2854 do_each_thread(g, p) {
2855 if (p->signal->tty == tty) {
2856 printk(KERN_NOTICE "SAK: killed process %d"
2857 " (%s): task_session(p)==tty->session\n",
2858 task_pid_nr(p), p->comm);
2859 send_sig(SIGKILL, p, 1);
2865 * We don't take a ref to the file, so we must
2866 * hold ->file_lock instead.
2868 spin_lock(&p->files->file_lock);
2869 fdt = files_fdtable(p->files);
2870 for (i = 0; i < fdt->max_fds; i++) {
2871 filp = fcheck_files(p->files, i);
2874 if (filp->f_op->read == tty_read &&
2875 file_tty(filp) == tty) {
2876 printk(KERN_NOTICE "SAK: killed process %d"
2877 " (%s): fd#%d opened to the tty\n",
2878 task_pid_nr(p), p->comm, i);
2879 force_sig(SIGKILL, p);
2883 spin_unlock(&p->files->file_lock);
2886 } while_each_thread(g, p);
2887 read_unlock(&tasklist_lock);
2891 static void do_SAK_work(struct work_struct *work)
2893 struct tty_struct *tty =
2894 container_of(work, struct tty_struct, SAK_work);
2899 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2900 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2901 * the values which we write to it will be identical to the values which it
2902 * already has. --akpm
2904 void do_SAK(struct tty_struct *tty)
2908 schedule_work(&tty->SAK_work);
2911 EXPORT_SYMBOL(do_SAK);
2913 static int dev_match_devt(struct device *dev, void *data)
2916 return dev->devt == *devt;
2919 /* Must put_device() after it's unused! */
2920 static struct device *tty_get_device(struct tty_struct *tty)
2922 dev_t devt = tty_devnum(tty);
2923 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2928 * initialize_tty_struct
2929 * @tty: tty to initialize
2931 * This subroutine initializes a tty structure that has been newly
2934 * Locking: none - tty in question must not be exposed at this point
2937 void initialize_tty_struct(struct tty_struct *tty,
2938 struct tty_driver *driver, int idx)
2940 memset(tty, 0, sizeof(struct tty_struct));
2941 kref_init(&tty->kref);
2942 tty->magic = TTY_MAGIC;
2943 tty_ldisc_init(tty);
2944 tty->session = NULL;
2946 tty->overrun_time = jiffies;
2947 tty_buffer_init(tty);
2948 mutex_init(&tty->legacy_mutex);
2949 mutex_init(&tty->termios_mutex);
2950 mutex_init(&tty->ldisc_mutex);
2951 init_waitqueue_head(&tty->write_wait);
2952 init_waitqueue_head(&tty->read_wait);
2953 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2954 mutex_init(&tty->atomic_read_lock);
2955 mutex_init(&tty->atomic_write_lock);
2956 mutex_init(&tty->output_lock);
2957 mutex_init(&tty->echo_lock);
2958 spin_lock_init(&tty->read_lock);
2959 spin_lock_init(&tty->ctrl_lock);
2960 INIT_LIST_HEAD(&tty->tty_files);
2961 INIT_WORK(&tty->SAK_work, do_SAK_work);
2963 tty->driver = driver;
2964 tty->ops = driver->ops;
2966 tty_line_name(driver, idx, tty->name);
2967 tty->dev = tty_get_device(tty);
2971 * deinitialize_tty_struct
2972 * @tty: tty to deinitialize
2974 * This subroutine deinitializes a tty structure that has been newly
2975 * allocated but tty_release cannot be called on that yet.
2977 * Locking: none - tty in question must not be exposed at this point
2979 void deinitialize_tty_struct(struct tty_struct *tty)
2981 tty_ldisc_deinit(tty);
2985 * tty_put_char - write one character to a tty
2989 * Write one byte to the tty using the provided put_char method
2990 * if present. Returns the number of characters successfully output.
2992 * Note: the specific put_char operation in the driver layer may go
2993 * away soon. Don't call it directly, use this method
2996 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2998 if (tty->ops->put_char)
2999 return tty->ops->put_char(tty, ch);
3000 return tty->ops->write(tty, &ch, 1);
3002 EXPORT_SYMBOL_GPL(tty_put_char);
3004 struct class *tty_class;
3007 * tty_register_device - register a tty device
3008 * @driver: the tty driver that describes the tty device
3009 * @index: the index in the tty driver for this tty device
3010 * @device: a struct device that is associated with this tty device.
3011 * This field is optional, if there is no known struct device
3012 * for this tty device it can be set to NULL safely.
3014 * Returns a pointer to the struct device for this tty device
3015 * (or ERR_PTR(-EFOO) on error).
3017 * This call is required to be made to register an individual tty device
3018 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3019 * that bit is not set, this function should not be called by a tty
3025 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3026 struct device *device)
3029 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
3031 if (index >= driver->num) {
3032 printk(KERN_ERR "Attempt to register invalid tty line number "
3034 return ERR_PTR(-EINVAL);
3037 if (driver->type == TTY_DRIVER_TYPE_PTY)
3038 pty_line_name(driver, index, name);
3040 tty_line_name(driver, index, name);
3042 return device_create(tty_class, device, dev, NULL, name);
3044 EXPORT_SYMBOL(tty_register_device);
3047 * tty_unregister_device - unregister a tty device
3048 * @driver: the tty driver that describes the tty device
3049 * @index: the index in the tty driver for this tty device
3051 * If a tty device is registered with a call to tty_register_device() then
3052 * this function must be called when the tty device is gone.
3057 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3059 device_destroy(tty_class,
3060 MKDEV(driver->major, driver->minor_start) + index);
3062 EXPORT_SYMBOL(tty_unregister_device);
3065 * __tty_alloc_driver -- allocate tty driver
3066 * @lines: count of lines this driver can handle at most
3067 * @owner: module which is repsonsible for this driver
3068 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3070 * This should not be called directly, some of the provided macros should be
3071 * used instead. Use IS_ERR and friends on @retval.
3073 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3074 unsigned long flags)
3076 struct tty_driver *driver;
3079 return ERR_PTR(-EINVAL);
3081 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3083 return ERR_PTR(-ENOMEM);
3085 kref_init(&driver->kref);
3086 driver->magic = TTY_DRIVER_MAGIC;
3087 driver->num = lines;
3088 driver->owner = owner;
3089 driver->flags = flags;
3090 /* later we'll move allocation of tables here */
3094 EXPORT_SYMBOL(__tty_alloc_driver);
3096 static void destruct_tty_driver(struct kref *kref)
3098 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3100 struct ktermios *tp;
3103 if (driver->flags & TTY_DRIVER_INSTALLED) {
3105 * Free the termios and termios_locked structures because
3106 * we don't want to get memory leaks when modular tty
3107 * drivers are removed from the kernel.
3109 for (i = 0; i < driver->num; i++) {
3110 tp = driver->termios[i];
3112 driver->termios[i] = NULL;
3115 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3116 tty_unregister_device(driver, i);
3119 proc_tty_unregister_driver(driver);
3120 driver->ttys = NULL;
3121 driver->termios = NULL;
3123 cdev_del(&driver->cdev);
3125 kfree(driver->ports);
3129 void tty_driver_kref_put(struct tty_driver *driver)
3131 kref_put(&driver->kref, destruct_tty_driver);
3133 EXPORT_SYMBOL(tty_driver_kref_put);
3135 void tty_set_operations(struct tty_driver *driver,
3136 const struct tty_operations *op)
3140 EXPORT_SYMBOL(tty_set_operations);
3142 void put_tty_driver(struct tty_driver *d)
3144 tty_driver_kref_put(d);
3146 EXPORT_SYMBOL(put_tty_driver);
3149 * Called by a tty driver to register itself.
3151 int tty_register_driver(struct tty_driver *driver)
3159 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
3160 p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
3165 * There is too many lines in PTY and we won't need the array there
3166 * since it has an ->install hook where it assigns ports properly.
3168 if (driver->type != TTY_DRIVER_TYPE_PTY) {
3169 driver->ports = kcalloc(driver->num, sizeof(struct tty_port *),
3171 if (!driver->ports) {
3177 if (!driver->major) {
3178 error = alloc_chrdev_region(&dev, driver->minor_start,
3179 driver->num, driver->name);
3181 driver->major = MAJOR(dev);
3182 driver->minor_start = MINOR(dev);
3185 dev = MKDEV(driver->major, driver->minor_start);
3186 error = register_chrdev_region(dev, driver->num, driver->name);
3192 driver->ttys = (struct tty_struct **)p;
3193 driver->termios = (struct ktermios **)(p + driver->num);
3195 driver->ttys = NULL;
3196 driver->termios = NULL;
3199 cdev_init(&driver->cdev, &tty_fops);
3200 driver->cdev.owner = driver->owner;
3201 error = cdev_add(&driver->cdev, dev, driver->num);
3203 goto err_unreg_char;
3205 mutex_lock(&tty_mutex);
3206 list_add(&driver->tty_drivers, &tty_drivers);
3207 mutex_unlock(&tty_mutex);
3209 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3210 for (i = 0; i < driver->num; i++) {
3211 d = tty_register_device(driver, i, NULL);
3218 proc_tty_register_driver(driver);
3219 driver->flags |= TTY_DRIVER_INSTALLED;
3223 for (i--; i >= 0; i--)
3224 tty_unregister_device(driver, i);
3226 mutex_lock(&tty_mutex);
3227 list_del(&driver->tty_drivers);
3228 mutex_unlock(&tty_mutex);
3231 unregister_chrdev_region(dev, driver->num);
3232 driver->ttys = NULL;
3233 driver->termios = NULL;
3234 err_free_p: /* destruct_tty_driver will free driver->ports */
3238 EXPORT_SYMBOL(tty_register_driver);
3241 * Called by a tty driver to unregister itself.
3243 int tty_unregister_driver(struct tty_driver *driver)
3247 if (driver->refcount)
3250 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3252 mutex_lock(&tty_mutex);
3253 list_del(&driver->tty_drivers);
3254 mutex_unlock(&tty_mutex);
3258 EXPORT_SYMBOL(tty_unregister_driver);
3260 dev_t tty_devnum(struct tty_struct *tty)
3262 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3264 EXPORT_SYMBOL(tty_devnum);
3266 void proc_clear_tty(struct task_struct *p)
3268 unsigned long flags;
3269 struct tty_struct *tty;
3270 spin_lock_irqsave(&p->sighand->siglock, flags);
3271 tty = p->signal->tty;
3272 p->signal->tty = NULL;
3273 spin_unlock_irqrestore(&p->sighand->siglock, flags);
3277 /* Called under the sighand lock */
3279 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3282 unsigned long flags;
3283 /* We should not have a session or pgrp to put here but.... */
3284 spin_lock_irqsave(&tty->ctrl_lock, flags);
3285 put_pid(tty->session);
3287 tty->pgrp = get_pid(task_pgrp(tsk));
3288 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3289 tty->session = get_pid(task_session(tsk));
3290 if (tsk->signal->tty) {
3291 printk(KERN_DEBUG "tty not NULL!!\n");
3292 tty_kref_put(tsk->signal->tty);
3295 put_pid(tsk->signal->tty_old_pgrp);
3296 tsk->signal->tty = tty_kref_get(tty);
3297 tsk->signal->tty_old_pgrp = NULL;
3300 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3302 spin_lock_irq(&tsk->sighand->siglock);
3303 __proc_set_tty(tsk, tty);
3304 spin_unlock_irq(&tsk->sighand->siglock);
3307 struct tty_struct *get_current_tty(void)
3309 struct tty_struct *tty;
3310 unsigned long flags;
3312 spin_lock_irqsave(¤t->sighand->siglock, flags);
3313 tty = tty_kref_get(current->signal->tty);
3314 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
3317 EXPORT_SYMBOL_GPL(get_current_tty);
3319 void tty_default_fops(struct file_operations *fops)
3325 * Initialize the console device. This is called *early*, so
3326 * we can't necessarily depend on lots of kernel help here.
3327 * Just do some early initializations, and do the complex setup
3330 void __init console_init(void)
3334 /* Setup the default TTY line discipline. */
3338 * set up the console device so that later boot sequences can
3339 * inform about problems etc..
3341 call = __con_initcall_start;
3342 while (call < __con_initcall_end) {
3348 static char *tty_devnode(struct device *dev, umode_t *mode)
3352 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3353 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3358 static int __init tty_class_init(void)
3360 tty_class = class_create(THIS_MODULE, "tty");
3361 if (IS_ERR(tty_class))
3362 return PTR_ERR(tty_class);
3363 tty_class->devnode = tty_devnode;
3367 postcore_initcall(tty_class_init);
3369 /* 3/2004 jmc: why do these devices exist? */
3370 static struct cdev tty_cdev, console_cdev;
3372 static ssize_t show_cons_active(struct device *dev,
3373 struct device_attribute *attr, char *buf)
3375 struct console *cs[16];
3381 for_each_console(c) {
3386 if ((c->flags & CON_ENABLED) == 0)
3389 if (i >= ARRAY_SIZE(cs))
3393 count += sprintf(buf + count, "%s%d%c",
3394 cs[i]->name, cs[i]->index, i ? ' ':'\n');
3399 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3401 static struct device *consdev;
3403 void console_sysfs_notify(void)
3406 sysfs_notify(&consdev->kobj, NULL, "active");
3410 * Ok, now we can initialize the rest of the tty devices and can count
3411 * on memory allocations, interrupts etc..
3413 int __init tty_init(void)
3415 cdev_init(&tty_cdev, &tty_fops);
3416 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3417 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3418 panic("Couldn't register /dev/tty driver\n");
3419 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3421 cdev_init(&console_cdev, &console_fops);
3422 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3423 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3424 panic("Couldn't register /dev/console driver\n");
3425 consdev = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3427 if (IS_ERR(consdev))
3430 WARN_ON(device_create_file(consdev, &dev_attr_active) < 0);
3433 vty_init(&console_fops);